Electrode or separator plates for fuel cells, i.e. in the form of anode or cathode plates, need to meet stringent requirements to avoid or remove any contamination, and typically require a series of different processing steps to be applied before the plates can be assembled into a fuel cell stack. Various types of coatings and other surface treatments may be required, which may need to be carried out in an enclosed chamber, for example in a vapour or ion deposition process. To prevent the risk of non-adherence of coatings, the surfaces of the plates to be coated must first be free of organic contaminants such as grease or oil. The preceding stamping operations used for applying surface features to the plates cannot however be generally assumed to be clean processes, which results in a significant risk of cross-contamination. The raw material, which may be in the form of a sheet metal roll, also cannot be assumed to be clean. Given that volume production of fuel cell parts requires a large number of such plates to be handled in rapid succession, a solution that enables continuous feeding of metallic plates through a batch type process is ideally required.
Current known processes for applying surface treatments to electrode plates include handling of individual plates and applying various surface treatments to the plates individually, as for example disclosed in US 2005/0241732, in which pressed plates are treated with a passivating solution followed by rinsing and drying steps.
A problem with existing processes is that automated handling of individual plates involves complex machinery.
A further problem, in particular in relation to fuel cell electrode or separator plates, is that such plates are thin and may be prone to damage by being handled individually.
A further problem is, on a mass-production scale where hundreds of thousands of plates are to be processed, how to handle batches of plates between processes, some of which may require a break in a production line.
A further problem is how to minimise on use of resources such as solutions for surface treatment and to reduce energy usage for applying other treatments such as surface deposited layers.
A further problem is how to minimise the space required for surface treatment apparatus configured to handle many thousands of plates in rapid succession.
It is an object of the invention to address one or more of the above mentioned problems.